The use of optical waveguides in their different forms has become prevalent across markets and applications. Optical waveguides in the form of optical fibers are the most common means for transporting telecommunication and data-communication signals across oceans, continents and all the way to individual homes. In medicine, optical fibers are widely used for endoscopy, in vivo and in vitro diagnostics, surgery and many other applications. Optical fibers are also used as part of sensing systems for monitoring temperature and stress on large infrastructure projects (e.g., bridges) and within deep oil wells.
A different type of optical waveguide is created on flat-round wafers (usually made of silicon) using technologies similar to the ones used for creating electronic “chips”. These “planar waveguides” form part of optical chips also known as Planar Lightwave Circuits (PLC). PLC chips are more sophisticated than bare optical fibers and are used to manipulate light by splitting its power, switching it to different paths, time modulating it or dispersing it to its different components (i.e., wavelengths).
The use of waveguide chips in bio-sensing applications has been described in U.S. Pat. No. 7,951,583 B2, U.S. Pat. No. 8,187,866 B2 and U.S. Pat. No. 8,288,157 B2. In these type of application it is advantageous to have the sensing chip partially encapsulated in a cartridge (preferably low-cost) or housing which serves to conveniently handle the small chip, accept the biological sample to be tested, store reagents needed to run the test, introduce the sample and reagents to the sensing chip and allow easy insertion of the sensing chip into the optical reader.